1. Field of the Invention
The present invention relates to construction materials, and particularly relates to a convection baffle for a hollow block providing thermal insulation, with the baffle increasing the R-value of the hollow block.
2. Description of the Related Art
In nations where hot weather prevails throughout most of year, such as the Kingdom of Saudi Arabia, a substantial amount of the total power consumption in the nation is expended cooling buildings by air conditioning. Electrical energy is primarily generated through the burning of fossil fuels, which release harmful gases, typically referred to as “greenhouse gases”, into the atmosphere. These greenhouse gas emissions contribute to global warming and major changes in climate conditions. At least one-half of the volume of emissions from the power production process is in the form of harmful greenhouse gases.
Thus, sustainability and energy savings are important issues aimed at the reduction of energy consumption and production of greenhouse gas emissions. Therefore, it is necessary to improve the thermal loss standards of building construction elements.
Heat leak calculations are of particular importance, since thermal energy transfer through constructions materials (such as wall-forming bricks) directly relates to energy conservation in buildings, and ultimately determines the suitable R-value or U-factor for building elements. In calculating air conditioning cooling load, the heat transmission through walls, in particular, is considered as a major element contributing to loss of efficiency by heating the cooler, air-conditioned air inside the building.
A substantial amount of energy is consumed to compensate for heat transfer through building walls and ceilings. During the mid-1970's, designers first became aware of the life-cycle cost of buildings, thus initiating the design of energy efficient walls. Walls using hollow blocks were built for their structural and moisture diverting qualities. Hollow blocks are manufactured in a wide variety of styles and sizes. FIG. 3 illustrates a typical hollow block B of the type commonly referred to as a multiple-core hollow block or concrete masonry unit.
Hollow block B typically is substantially rectangular, having opposed upper and lower surfaces 110, 112, a pair of laterally opposed sidewalls 102, 104, and a plurality of open passages P defining cores formed transversely therethrough. Alternatively, block B may be described as a rectangular prism having a plurality of medial partition walls defining multiple cores through the block B. Today, hollow and dense cement or concrete blocks, also sometimes referred to as hollow blocks, are suitable and common alternatives to conventional bricks or construction blocks, and are widely used in construction. A typical block B, such as that shown in FIG. 3, may have a lateral width of approximately 20 cm, a height of approximately 20 cm and a transverse length of approximately 40 cm. As shown, nine 5 cm by 5 cm passages P are arranged as a 3×3 matrix or array, with the passages P extending transversely through block B. Passages P form air-filled cavities when blocks B are used to construct building facades.
Such hollow blocks are typically formed from cement, stone chips, stone dust or sand, and are not only cheaper to manufacture than conventional bricks or blocks, but have useful thermal properties. The modes by which heat transfer occurs include heat conduction in the solid sections of block B, along with natural convection and radiation transfer within the passages P. The outer surface 102 is exposed to solar radiation having a temperature of Th, and the inner surface 104 is cooled by interior air conditioning, having a temperature of Tc, thus providing a thermal gradient for heat transfer to take place. The rate of heat transfer depends upon the material properties, shape and thermal parameters of the block. Typically, in the prior art hollow block B shown in FIG. 3, insulation is inserted within the passages P. In order to conserve energy through reduction of powered air conditioning within a building, constructing a block having optimal insulating properties, or a high R-value, is needed. Varying insulation material filling passages P, or varying the size, contouring and number of passages P typically only allows for variation in R-value of between approximately 20% and 30%. Thus, a convection baffle for hollow blocks solving the aforementioned problems is desired.